The present invention relates to a tensioner for tensioning belt or chain for internal combustion engines.
A tensioner is used to apply a constant tension on a belt o chain, directly or indirectly by means of a pulley or the like. A basic construction is such that a tension rod urged by a compression spring is mounted slidably in a casing. In this type of tensioner, it is possible that the tension rod may be urged so excessively that it will fly out of the casing accidentally. Therefore, the tensioner is provided with a stopper pin for locking the tension rod when not in use. A conventional stopper pin is inserted in a small hole formed on the casing and the tension rod for locking the tension rod when not in use. After fixing the tensioner on equipment, the stopper pin is taken off so as to unlock the tension rod.
However, in this type of locking system, it is necessary to position holes on the casing and the tension rod, and that positioning is very hard, because of only one locking position on the whole stroke of tension rod, not permitting locking in any place.
Therefore, a locking system has been disclosed by a Japanese Patent Application wherein an extension on the rear end of tension rod is used for positioning. As shown in FIG. 7, a tension rod 201 is slidably supported by a bearing 202a, of which tail portion 201a is used so as to form a pluraltiy of through holes 203 in it. Numberal 205 indicates a compression spring for urging the tension rod 201.
The tension rod 201 can be locked in various positions by a stopper pin 204 inserted in the through holes 203 on the tail portion 201a so that the tension rod may stay in necessary position for storage and maintenance.
Consequently, the dimensional size of this type of tensioner 200 became excessively large because tail portion 201a extended from the rear end of casing 202, resulting in difficult installation in limited space and causing an increase of weight.
The present invention was developed considering the above situations and is to provide a light and compact tensioner having a locking system in various positions.